Method and system for transporting oil by pipe line

ABSTRACT

System and method for transporting oil by pipe line under or over frozen ground, e.g., permanently frozen terrain, without melting or softening the ground by heat transfer from the oil, by passing oil through a pipe line supported by such frozen ground or terrain, placing a second pipe line for carrying a fluid refrigerant, particularly liquid natural gas, along and closely adjacent to the oil pipe line but spaced therefrom, the second pipe line also being supported by the frozen ground, and being disposed adjacent to the frozen ground, providing insulation between the oil and refrigerant, e.g., liquid natural gas, pipe lines, as by placing the oil pipe line in an excavation in the ground and positioning the liquid natural gas pipe line in such excavation below and parallel to the oil pipe line, with gravel, for example, filling the spaces in the excavation and between the two pipe lines, passing a liquid refrigerant such as liquid natural gas through the second pipe line at a temperature substantially below the temperature of the adjacent frozen ground, thereby maintaining the ground around the pipe lines frozen without cooling the oil in the oil pipe line down to a temperature which substantially retards flow of the oil in the oil pipe line. As a feature of the invention, a minor portion of the liquid natural gas at each pumping station can be used for operating both the oil pump or pumps and liquid natural gas pump or pumps at the respective stations. The result is that the ground supporting or surrounding the oil pipe line remains in permanently frozen condition to firmly support such pipe line at all times, and at the same time liquid natural gas can be transported to market and a portion thereof employed to operate the pumping stations.

United States Patent Sparling [451 Mar. 21, 1972 [54] METHOD AND SYSTEMFOR TRANSPORTING OIL BY PIPE LINE Joseph T. Sparling, 1295 Acadia Road,Vancouver, 8 British Columbia, Canada [22] Filed: Apr. 2, 1970 [21]Appl.No.: 25,029

[72] Inventor:

3,287,914 11/1966 Faulconer et al. ..6l/.5 3,217,791 ll/l965 Long..l66/DIG. 1

OTHER PUBLICATIONS Alaskan Completions Will Be Complicated World Oil p.85,,Ianuary, 1970.

Primary ExaminerMeyer Perlin Assistant Examiner- Ronald C. CaposselaAtt0rney-Max Geldin [57] ABSTRACT System and method for transporting oilby pipe line under or over frozen ground, e.g., permanently frozenterrain, without melting or softening the ground by heat transfer fromthe oil, by passing oil through a pipe line supported by such frozenground or terrain, placing a second pipe line for carrying a fluidrefrigerant, particularly liquid natural gas, along and closely adjacentto the oil pipe line but spaced therefrom, the second pipe line alsobeing supported by the frozen ground, and being disposed adjacent to thefrozen ground, providing insulation between the oil and refrigerant,e.g., liquid natural gas, pipe lines, as by placing the oil pipe line inan excavation in the ground and positioning the liquid natural gas pipeline in such excavation below and parallel to the oil pipe line, withgravel, for example, filling the spaces in the excavation and betweenthe two pipe lines, passing a liquid refrigerant such as liquid naturalgas through the second pipe line at a temperature substantially belowthe temperature of the adjacent frozen ground, thereby maintaining theground around the pipe lines frozen without cooling the oil in the oilpipe line down to a temperature which substantially retards flow of theoil in the oil pipe line. As a feature of the invention, a minor portionof the liquid natural gas at each pumping station can be used foroperating both the oil pump or pumps and liquid natural gas pump orpumps at the respective stations. The result is that the groundsupporting or surrounding the oil pipe line remains in permanentlyfrozen condition to firmly support such pipe line at all times, and atthe same time liquid natural gas can be'transported to market and aportion thereof employed to operate the pumping stations.

22 Claims, 10 Drawing Figures PAIENTEDMARZI I972 SHEET 1 OF 3 INVENTOR.JOSEPH 'Z. SPAQL/AJG #7 TOP J5 V PAIENTEUMARZI I972 SHEET 2 [IF 3\JOSEPH T. SPQEA M36 PATENTEDHARZI x972 3,650,119

SHEET 3 [IF 3 Q-r- OPA Ev METHOD AND SYSTEM FOR TRANSPORTINGOIL BY PIPELINE A particularly prolific oil field has been recently discovered andbegun to be developed on the North Slope of Alaska. The most feasibleway to transport such oil across Alaska to terminals in southern Alaskafor transport to United States West Coast ports and to far easternmarkets such as Japan, is by oil pipe line from the North Slope southacross Alaska.

However, a substantial portion of the terrain in this region is tundra,which, if undisturbed, remains frozen most of the year but will melt ifthere is any activity in the vicinity. For this reason, the drillingrigs at the North Slope, town sites in the vicinity, and otheractivities of this nature, are all generally set upon a bed of gravel ofthe order of about 5 feet thick, in order to form a base that will allowfor transportation and footings for structures without disturbing thetundra.

However, a considerable problem is involved in laying a pipe line over alarge distance of several hundreds of miles over such tundra,particularly in establishing a suitable foundation for the oil pipeline, since as previously noted the danger exists of the tundra beneaththe right of way melting and causing serious damage or collapse of thepipe line, resulting from such insecure base. For this reason variousproposals have been made for supporting the oil pipe line passingthrough or across such generally frozen terrain. Thus, for example, ithas been proposed to support the oil pipe line on a platform positionedseveral feet, for example, about feet, above the ground by driving pilesor stilts into the tundra to support a platform for the oil pipe line.However, this would result in a highly expensive system with the pipeline situated above the ground on a platform, thus providingobstructions for animals, and would still be subject to the danger ofcollapse of the tundra by the weight of the line and oil passingtherethrough. While it has also been proposed to lay the oil pipe lineon a gravel bed positioned on the surface of the tundra, here also thereis a danger of possible melting of the tundra beneath the gravel bed,endangering the line, and the exposed line also presents an obstructionto animals, and objections from ecologists. The pumping of the oilthrough a pipe line, such as a proposed 48-inch oil pipe line requiresthat the oil be kept at temperatures above freezing and as a result thepipe line must be layed above ground, e.g., on a bed of gravel or tundraas previously noted. This is extremely expensive and still does notinsure the stability of the permafrost areas. Thus, to date noacceptable or feasible system has been proposed, to applicant'sknowledge, for constructing and properly supporting a pipe line acrossthe above noted permafrost tundra without serious danger of collapse ofthe line as result of melting and instability of the frozen ground, andavoiding ecological objections.

The North Slope Alaskan oil field has also a very considerable amount ofnatural gas which requires shipment to market. However, the presentpractice is to flare the gas to the atmosphere, which is frowned upon bythe authorities as a pollution hazard, and as a waste of naturalresources, and in many areas of this region, the well operators areeither penalized for this practice or made to reinject the gas into theformation, both of which are expensive and undesirable.

The above problems and disadvantages can be overcome and a feasible andpractical method and system are provided for transporting oil through apipe line across the frozen terrain while maintaining such terrain orground permanently frozen and providing a stable bed for the pipe line,in accordance with the concept of the present invention. In accordancewith the present invention, by liquefying the natural gas at the .wellhead, and transporting such liquid natural gas through a pipe lineplaced beneath the crude oil line and supporting such oil pipe line on arelatively thin gravel bed, for example, the cold from the liquidnatural gas which is at a temperature, e.g., of the order of about 260F., can be used to maintain a below freezing temperature on the pipeline rightof-way, and maintaining a stable support for the pipe line.Thus, in accordance with the invention concept, the liquid natural gasline maintains the terrain along the right-of-way permanently frozen,but by providing suitable insulation between the liquid natural gas andoil pipe line, as by an intervening bed of gravel, the liquid naturalgas line does not cool the oil in the oil pipe line to a point at whichit substantially reduces the flow of the oil in the oil pipe line.

The oil pipe line is preferably placed below the surface of the groundor terrain, as by placing the pipe line in a relatively shallowexcavation, with the liquid natural gas pipe line placed a shortdistance below the oil pipe line in the excavation, with gravel placedin the excavation and between the two pipe lines, according to certainpreferred embodiments described below, and which can also includepreferably an additional supporting member for the oil pipe line, in theform of a trough or cradle. This arrangement accomplishes the main objects of the invention, which are to maintain the supporting terrain orground along the right-of-way permanently frozen, while pennitting theoil to flow freely through the oil pipe line. Such preferred undergroundarrangement also has the advantages that the larger oil pipe line doesnot disturb the ecology, which would be the case if the line were laidover the ground, and is not subject to damage by animals, and is not ahazard to animals. Also, placement of the oil pipe line and liquidnatural gas line below the ground surface has a further advantage thattemperature variations due to change in climatic conditions are notnearly as severe when the pipes are laid underground as compared tobeing placed above the ground. Further, when the oil pipe line is placedabove the ground, slack loops or expansion joints are required, which isexpensive.

The crude oil pipe line pump stations are spaced at various distancesalong the line depending upon the pressure required to cross over theterrain between stations. The natural gas is liquefied at the well headand transported along the right of way according to the invention in theliquid natural gas pipe line or lines from one pumping station to thenext in a manner allowing the temperature to be controlled so that theliquid natural gas maintains the desired ground temperature when itarrives at each of the successive stations. Due to rise of temperatureof the liquid natural gas between stations, at each station means areprovided, in the form of a small liquefaction installation, to againreduce the temperature of the liquid natural gas to that at thepreceding station. As additional features of the invention, smallamounts of natural gas can be bypassed at each station to operate theoil pump or pumps and also the liquid natural gas pump or pumps and anyother auxiliary equipment, thereby reducing the cost of operation of thepipe line. Further, liquid natural gas can be bled from the liquidnatural gas line at any desired locations along the line to servecommunities or industry along the right-of-way.

Thus, the present invention accomplishes the following objects andachieves the following advantages:

It allows for the maintaining of a suitable soil or ground conditionalong the entire oil pipe line right-of-way, providing a stable supportfor the line at all times, thus reducing the oil pipe line constructioncosts and problems; it allows the pumping stations along the line to beoperated economically and conveniently on natural gas; it provides ameans to bring well head natural gas, presently being flared orreinjected, to tidewater and market along the same right-of way andtogether with the oil; it materially reduces the cost of construction ofthe liquid natural gas pipe line and indeed such liquid natural gas linecan be installed at substantially no additional cost, since the savingseffected by the method of pipe line construction for the oil lineaccording to the invention, and the operation of pump stations onnatural gas, will pay for the liquefaction of the natural gas and atleast part of the cost of the liquid natural gas line.

The invention will be more readily understood by the description belowof certain embodiments of the invention, taken in connection with theaccompanying drawings wherein:

FIG. 1 is a cross sectional illustration of an oil pipe line and aliquid natural gas line positioned in an excavation in the ground, andinsulated with gravel and by other means, in accordance with theinvention;

FIG. 2 is a cross sectional illustration similar to FIG. 1, showinganother embodiment of the invention; particularly applicable wheredetrimental permafrost is encountered;

FIG. 3 is a plan view of the embodiment illustrated in FIG. 2, partlybroken away for clarity;

FIG. 4 is a cross sectional illustration similar to FIG. 1, of stillanother embodiment of the invention;

FIG. 5 illustrates a modification of the embodiment illustrated in FIG.1;

FIGS. 6, 7 and 8 illustrate further embodiments of the inventionconcept, wherein the oil pipe line is disposed above the ground orterrain;

FIG. 9 is a schematic representation of the oil pipe line and liquidnatural gas pipe line positioned along the same right-ofway, with therespective pumping stations for each line, and illustrating thebypassing of natural gas at each pumping station for operating the pumpsand liquefaction apparatus; and

FIG. 10 is a schematic representation of a means for initially insuringa frozen terrain along the right-of-way, prior to commencing flow of oilin the oil pipe line, by recirculation of liquid natural gas betweenpairs of successive stations along the line.

The drawings are exaggerated for greater clarity.

Referring to FIG. 1 of the drawing, numeral 10 illustrates a system inwhich an excavation, e.g., about 8 feet deep and about 6 feet wide, asindicated at 12, is made in the ground, indicated at 14. A liquidnatural gas line 16, e.g., from about 6 inches to about 1 foot indiameter, is placed centrally at the bottom of the excavation 12, andgravel, indicated at 18, is placed in the bottom of the excavationaround the liquid natural gas pipe line up to the top of such line. AU-shaped member or trough 20, constructed of a lightweight insulationmaterial of high strength, e. g., a lightweight chemical concreteconstruction material, and having a transverse dimension of about 50inches to about 54 inches across the sides 21 of the trough, is placedcentrally over the gravel bed 18 in the bottom of the trough and on theupper surface of the liquid natural gas line, so that the trough restson such gravel and the liquid natural gas line.

The trough can be formed of any suitable material having high strengthand which provides a high thermal barrier and is resistant to corrosion.

An oil pipe line 22, e.g., of about 48 inches in diameter, is thenpositioned within the trough so that it essentially rests on the bottomthereof, and gravel, indicated at 24, is placed within the trough andaround the oil pipe line 22 and fills the crevices between the oil pipeline and the sides of the trough, up to ground level, as indicated at26. Gravel is also placed within the excavation around the outersurfaces of the sides of the trough 20, as indicated at 28, up to groundlevel 26, thus substantially filling the excavation and the trough withgravel around the liquid natural gas and oil pipe lines 16 and 22,respectively. If desired, although not necessary, a cover indicated at30 can be positioned over the upper end of the trough 20. Viewing FIG.1, it will be seen that the liquid natural gas line withdraws heat fromthe surrounding ground 14 both below and around the sides of theexcavation 12, serving to maintain such ground permanently frozen andprovide a stable bed for the oil pipe line 22 along the right-of-way.However, as result of the assembly shown in FIG. 1, including theinsulating gravel around and between the liquid natural gas and oil pipelines, and the lightweight insulation trough 20 between the two lines,and which also tends to further support the pipe line 22 within theexcavation, sufficient insulation is provided between the oil pipe line22 and the liquid natural gas line 16 so that although the liquidnatural gas cools the oil flowing in pipe 22 to some extent, thetemperature of the oil is maintained at a desirable pumping temperature,e.g., of the order of about 30 F.

Although gravel is a preferred insulation material, it will beunderstood that other bulk insulation materials such as earth (tundra)and sand can be employed for filling the trough 20 and excavation 12around the oil and liquid natural gas pipe lines, as desired. Alsoambient air can be used, e.g., for insulation within the trough aroundthe oil pipe line, as noted below. Preferred insulation materials aregravel and earth (tundra).

Thus, for example, again viewing FIG. 1, after forming the excavationl2, and placing the natural gas pipe 16 in position as shown in FIG. 1,the bottom of the excavation can be filled with tundra at 18, whichtundra was previously removed from the excavation, and the trough 20 andoil pipe 22 are placed in position as illustrated in FIG. 1, and thespaces around the trough at 28 and within the trough at 24 back filledwith additional tundra previously removed from the excavation. Suchreplacement and maintenance of the tundra would be ecologicallydesirable. Further, if desired, tundra can be placed in the excavationaround the outside of trough 20 and around the liquid natural gas (LNG)pipe 16, and gravel placed within the trough 20 and around the oil pipe22, or vice versa.

Further, if desired, again viewing FIG. 1, trough 20 can be reduced to acradle formed essentially only of the bottom portion 31 of the troughshown in FIG. 1, and not containing the vertical sides 21 above thedotted lines indicated at 33. Under these conditions the two gravel ortundra beds at 24 and 28 from a single insulation bed around the upperportion of the oil pipe 22 above the cradle.

The embodiments described above and illustrated in FIG. 1 are preferredembodiments:

Referring now to' FIG. 2, here again excavation 18 is provided in theground 14, and a liquid natural gas pipe line 16 is also placedcentrally in the bottom of the excavation, and an insulation materialsuch as gravel, indicated at 32, is then placed in the excavation aroundand above the liquid natural gas line, e.g., for a height of about 1 to1% feet above the liquid natural gas line. The oil pipe line 22 is thenplaced on such gravel bed and held in position in the gravel bed bymeans of river weights 34, e.g., of concrete, placed around the oil pipeline at intervals along the line, as further illustrated in FIG. 3. Theexcavation is then back filled with insulation material such as gravel,indicated at 36, up to the ground level 26 within the excavation, sothat the oil pipe line 22 is completely embedded in gravel within theexcavation below the upper surface of the gravel bed 36. The riverweights 34 not only maintain the oil pipe line 22 in position in thegravel bed, but in the event of the presence of any water flowing intoor formed in the excavation around the pipe 22, which would cause it tofloat upward, and forming a detrimental permafrost, the river weightsprevent this from occuring.

As in the embodiment illustrated in FIG. 1, in the present modificationof FIGS. 2 and 3, liquid natural gas passing through line 16 maintainsthe ground 14 below the excavation and around the excavation permanentlyfrozen, but asresult of the gravel insulation between liquid natural gaspipe line 16 and the oil pipe line 22, the oil flowing through line 22is maintained in a free flowing condition.

Now referring to FIG. 4, illustrating a further modification of thesystem of FIG. 1, the liquid natural gas line and lightweight insulationtrough 20 are placed within the excavation 12 and gravel or earth(tundra) indicated at 18 and at 28 are placed within the excavationaround the liquid natural gas line 16 and the outer surfaces of thetrough 20, up to the ground level 26, as in the caseof FIG. 1.

However,.in the embodiment of FIG. 4, a supporting insulating block 38is positioned at intervals along the bottom of the trough 20, and theoil pipe line is supported on such blocks, with the sides of the line 22substantially in contact with the inner surfaces of the trough 22, tomaintain the oil line in fixed position within the trough.

However, no solid insulation material such as gravel is placed withinthe trough 20, but rather ambientair is permitted to enter the space 40with the trough and around the oil line 22, to function as an insulationmedium. In this embodiment, the cover within is preferably placed overthe top of the open trough 20, to close same and prevent debris fromfalling into the trough around the pipe line, and also to prevent dangerto animals, humans and the like from falling into the trough and beinginjured.

The embodiment of FIG. 4 functions similarly to that of FIG. 1 in thatthe cold from the liquid natural gas line withdraws heat from thesurrounding ground and terrain l4, maintaining same permanently frozen,and the insulation means including the gravel beds 18 and 28, trough andthe air within the space 40 prevent undue lowering of the oiltemperature in line 22 and permits free flow thereof.

Now referring to the modifications of FIG. 5, this embodiment issubstantially the same as that of FIG. 1, except that in place ofemploying a single centrally disposed natural gas pipe line 16positioned at the bottom of the excavation below the oil pipe 22, thereare disposed two liquid natural gas pipe lines 16 positioned adjacentopposite corners of the excavation 12. This arrangement gives moreeffective and widespread cooling of the adjacent ground 14 by both ofthe liquid natural gas lines 16, to maintain the adjacent groundpermanently frozen, while the oil line 22 is still sufficientlyinsulated from both of the liquid natural gas lines 16 by theintervening gravel indicated at 18 and 28 and the insulating trough 20,so that the oil is maintained at a sufficiently high temperature to bereadily pumped.

In FIGS. 1, 4 and 5, it will be understood that the trough 20 or cradlesupporting the oil pipe line can have any desired shape, e.g.,rectangular, with a simple horizontal bottom portion and vertical sidesas at 21, without the sloping sides of bottom portion 31 of trough 20.

FIGS. 6, 7 and 8 illustrate further modifications of the inventionprinciples, wherein the oil pipe line is positioned above the surface ofthe ground. In FIG. 6, the liquid natural gas pipe line 16 is placed onthe surface 26 of the ground 14 along the pipe line right-of-way, and agravel bed indicated at 42 is then positioned over the right-of-way,covering and embedding the liquid natural gas line 16. There is placedon the top ofthe gravel bed 42, which can be, for example, about 3 toabout 4 feet high, the oil pipe line 22 which is disposed directly abovethe liquid natural gas line 16. Suitable supports, indicated at 44 inFIG. 6, can be disposed at intervals along the gravel bed 42 to maintainthe pipe line 22 in position on the gravel bed. It will be understoodthat any other suitable and conventional means can be employed tomaintain the oil pipe line 22 in position on the gravel bed.

FIG. 7 shows an arrangement similar to that of FIG. 6, except that inthe modification of FIG. 7, the liquid natural gas line 16 is buried inthe ground 14 so that the upper surface of the liquid natural gas lineis about at the level of the surface 26 of the ground.

In the modification of FIG. 8, the liquid natural gas line 16 is firstburied in the ground along the right-of-way, e.g., about 2 to about 2%feet below the ground level 26. A gravel bed 45 is placed in a shallowexcavation 47, above pipe line 16, and the oil pipe line 22 ispositioned along the top 49 of the gravel bed at ground level 26, withsuitable supporting means 44, noted above, or other equivalent means,employed to maintain the pipe line 22 in position along theright-of-way.

In all of the embodiments of FIGS. 6, 7 and 8, the liquid natural gaspipe line provides sufficient cold to maintain the adjacent terrainbelow the oil pipe line 22 permanently frozen, while the gravel bed 42in the embodiments of FIGS. 6 and 7, and the gravel bed 45 in FIG. 8,between the liquid natural gas line 16 and the oil pipe line 22,provides sufficient insulation to prevent undue reduction of thetemperature of the oil pipe line 22, and to permit such oil to flowfreely.

In all of the embodiments of FIGS. 1 to 8 described above, it will ofcourse be understood, and as illustrated in FIG. 9 below, that theliquid natural gas pipe line or lines 16 are positioned parallel to theoil pipe line 22 along the same right-ofway.

Now referring to FIG. 9, there is illustrated a pipe line arrangement 46comprising an oil pipe line 22 and a liquid natural gas pipe line system16, insulated from each other, as illustrated by any of the embodimentsof FIGS. 1 to 8 described above, along the same right-of-way. Thus, oiland gas are both produced at the well head indicated at 48, and the oil,generally at a temperature ranging from about F. to about 200 F. isconducted via pipe 50 to the oil pipe line 22. The natural gas isgathered and liquefied at a location near the terminus of the oil pipeline indicated at 52, and is then conducted via conduit 54 to the liquidnatural gas pipe line 16.

The oil in line 22 is pumped at successive pumping stations A, B, C, D,etc. along the entire right-of-way, the pumping stations being suitablyplaced depending upon the pressure required to traverse the terrainbetween successive stations. The liquid natural gas in the liquidnatural gas line 16 traverses the same right-of-way, as noted above,there being a series of successive liquid natural gas pumping stationsA, B, C, D, etc., corresponding to, and at the same correspondinglocations as the pumping stations A, B, C, D, etc. of the oil line 22.At each oil pumping station and at each liquid natural gas pumpingstation, it will be understood that there can be one or more pumps.

At station A, the oil from the well head is pumped to a suitablepressure to traverse the terrain between stations A and B, e.g., to apressure of about 1,000 p.s.i., and at each successive pumping stationB, C, D, etc. the oil is again pumped up to suitable pressure, e.g., ofthe order of about 1,000 p.s.i., to permit continuous uniform flow ofthe oil through the entire line.

The liquid natural gas in line 16 is generally operated at higherpressures to balance heat loss and maintain the gas in an essentiallyliquid condition between stations, e.g., at pressures of the order ofabout 1,500 to about 2,000 p.s.i., and which is at a temperature say ofabout 25 8 F. at the initial station A, and which temperature iscontrolled so that it will still maintain a desired ground temperaturesuch as to maintain the ground frozen between stations A and B, and Aand B, and will have its temperature raised, say about 100 F. to about-158 F., by heat transfer from the ground, when it reaches the stationB. Thus, the liquid natural gas between two successive pumping stationscan range from about 200 to about 275 F. at one station, and beingheated during passage from such station up to about 1 25 to about F. atthe next station. At the same time, during traversal of the oil fromstation A to B, the oil in line 22 will be cooled down say to about 30F., the latter temperature still permitting free flow and pumpability ofthe oil. At station B, the oil is pumped up again say to about 1,000p.s.i., such pumping increasing the temperature of the oil somewhat, andthe oil traverses the next stretch of distance between stations B and C.

At station B along the liquid natural gas line 16, the liquid naturalgas is passed through a liquefaction plant 56 to liquefy vapors ofnatural gas generated in the run between stations A and B, and theliquid natural gas, again reduced in temperature, e.g., down to about258 F., is pumped up if necessary at station B to the desired pumpingpressure, e.g., of about 1,500 to about 2,000 p.s.i. The liquid naturalgas as result of rise in temperature in passing from station A to B andsome resultant vaporization, expands and generates at least some of thepower required for pumping the liquid natural gas to the next station,but generally some mechanical pumping at station B is necessary for therun between stations B and C.

As previously noted, the oil will be cooled down to some extent by theliquid natural gas, but this is balanced to a degree by the linefriction in the oil line, and the temperature of the liquid natural gaswill be raised to some extent by the oil during traversal of the oil andliquid natural gas from stations A to B and A to B, respectively. Thistransfer of heat between the oil and liquid natural gas should beminimized as much as possible. This heat transfer mechanism can bebalanced so that the oil will be maintained at the most desirabletemperature for pumping, e.g., about 30 F., while the liquid natural gasis maintained at as low a temperature as possible, e.g., varying betweenl40 to about 260 F., in which event the cold from the liquid natural gasline will stabilize the soil along the right-of-way by maintaining it ata below freezing temperature so that it remains permanently frozen, asdescribed above.

At each station a small amount of liquid natural gas is bypassed, asindicated at 58, to operate the oil pump at the station, and starting atstation B, and at successive station C, D, etc. a minor portion ofliquid natural gas is bypassed from the line 16, as indicated at 60, tooperate the liquid natural gas liquefaction plant 56 and the liquidnatural gas pump at each such station. If desired, liquid natural gascan be bled from any place along the liquid natural gas line 16, asindicated at 62, to serve a community or an industry in the area.

Referring to H6. 10, there is illustrated a system for initiallyreducing the temperature of the ground adjacent the oil and liquidnatural gas pipe lines 22 and 16, prior to pumping of oil in line 22. Inthis arrangement another liquid natural gas line 64 is provided, andadjacent to successive stations, branch lines 66 and 68 are provided toform a closed circulation loop 16, 66, 64 and 68 between successiveliquid natural gas stations, e.g., between A and B, to providecirculation of liquid natural gas through each such loops for a periodof time sufficient to reduce the temperature of the ground along therightof-way between each pair of successive liquid natural gas stationsthe desired amount.

In each of these loops, the returning liquid natural gas is passed tothe liquefaction plant, e.g., 52 or 56, and then again pumped as at Afor passage again to the next station, e.g., B. A small amount of liquidnatural gas is bypassed at 70 and 72 from the return line 68 foroperation of the initial gas liquefaction plant 52 and the liquidnatural gas pump at that station, e.g., station A. A system of valves74, 76 and 78 is provided in each circulation loop to controlcirculation of the liquid natural gas through each of such loops, asdesired. Similar closed loops are provided between the successive pairsof stations such as between B and C, for circulation of liquid naturalgas between such stations. After the ground or terrain along theright-of-way has reached the desired reduced temperature to maintain theground frozen to form a stable support for the oil line, circulation ofthe liquid natural gas through the respective closed loops illustratedin FIG. is terminated, and the oil and liquid natural gas flow throughlines 22 and 16 is commenced, as described above and illustrated in FIG.9.

it will be understood that although the principles of the invention havebeen described particularly in relation to the use of liquid natural gasas fluid refrigerant to maintain the oil pipe line right-of-waypermanently frozen to support the oil line, other fluid refrigerantshaving suitable boiling points such as, for example, Freon l2 (boilingpoint, -28 C.) or other suitable refrigerants such as, for example,suitable brine solutions, can be passed through line 16, the refrigerantbeing chosen such that it can be maintained at sufficiently lowtemperatures to maintain a permanently frozen ground condition betweensuccessive stations for the above described purpose, while minimizingthe cooling down of the oil between stations, to permit facile pumpingof the oil.

As previously indicated, the arrangements of H68. 1 to 5, with the oilpipe line and liquid natural gas pipe line both positioned below theground are preferred arrangements while the embodiments of FIGS. 6, 7and 8, wherein the oil pipe line is disposed above the ground, althoughfunctioning to obtain the intended results, are not preferred, forreasons previously noted.

From the foregoing, it is seen that the invention provides a simple,economical and effective means for transporting oil, particularly incombination with the transport of liquid natural gas, along the sameright-of-way, with the chief advantage that the cold from the liquidnatural gas maintains the ground in a permanently frozen and stablecondition. Although the invention has particular inerit in transportingoil from the Alaskan oil fields, it will of course be obvious that thesesame principles can be employed for transporting oil across any otherregions, e.g., of the United States, Canada, the Scandinavian countries,Siberia or other regions of the earth where a perprovide a suitablestable base for oil pipe lines.

While I have described particular embodiments of my invention forpurposes of illustration, it will be understood that variations andmodifications will occur to those skilled in the art and the inventionis not to be taken as limited except by the scope of the appendedclaims.

I claim:

1. A method for transporting oil by pipe line across frozen groundwithout melting or softening the ground by heat transfer from the oil,which comprises passing oil through a pipe line supported by frozenground, said oil being at a temperature substantially above thetemperature of said ground, placing a second pipe line along and closelyadjacent to said oil pipe line but spaced therefrom, said second pipeline also being supported by said frozen ground, and being disposedadjacent to said frozen ground, providing insulation between said oiland second pipe lines, and passing liquid natural gas through saidsecond pipe line at a temperature substantially below the temperature ofthe adjacent frozen ground, thereby maintaining said last mentionedground frozen but without cooling the oil in the oil pipe line down to atemperature which would substantially reduce the flow of said oil insaid oil pipe line, including providing said oil and said natural gas ingaseous form from a common source, and liquefying said natural gas priorto passage thereof through said second pipe line.

2. A method as defined in claim 1, said insulation including a substanceselected from the group consisting of gravel, earth, sand and air.

3. A method as defined in claim 1, said insulation including a substanceselected from the group consisting of gravel and earth, and comprisingplacing said substance around said oil pipe line.

4. A method as defined in claim 1, including pumping said oil at aplurality of stations along said oil pipe line and pumping said liquidnatural gas at a plurality of stations along said second pipe line, thetemperature of said liquid natural gas increasing from one liquidnatural gas pumping station to the next liquid natural gas pumpingstation by removal of heat from said ground adjacent said oil pipe linebetween said last mentioned pumping stations, and reducing thetemperature of the natural gas at said next pumping stationsubstantially to the temperature of said natural gas at said precedingpumping station.

5. A method as defined in claim 4, a portion of said liquid natural gasbeing vaporized during passage thereof from said one liquid natural gaspumping station to said next liquid natural gas pumping station, andincluding liquefying said vaporized natural gas at said next liquidnatural gas pumping station for said reducing said temperature of saidliquid natural gas substantially to the temperature of said liquidnatural gas at said preceding pumping station.

6. A method as defined in claim 5, said oil pipe line pumping stationsand said liquid natural gas pipe line pumping stations beingrespectively positioned at adjacent locations along said respective pipelines, including bypassing a minor portion of liquid natural gas fromsaid liquid natural gas pipe line at each station thereof to theadjacent oil pipe line pumping station for operation of the pump at saidlast mentioned pumping station and to the pump at said liquid naturalgas pumping station, for operation of said respective pumps. I

7. A method as defined in claim 5, wherein the temperature of saidliquid natural gas between two successive liquid natural gas pumpingstations ranges from about 200 to about 275 F. at one station, and beingheated during passage from said one station up to about l25 to about l75F. at the next station.

8. A method as defined in claim 1, including initially circulatingliquid natural gas through said liquid natural gas pipe line in a closedloop between a pair of successive liquid natural gas pumping stations toreduce the temperature of the adjacent ground to insure that said groundis initially in a frozen condition, prior to passing oil through saidoil pipe line.

9. A method for transporting oil by pipe line across frozen groundwithout melting or softening the ground by heat transfer from the oil,which comprises passing oil through a pipe line supported by frozenground, said oil being at a temperature substantially above thetemperature of said ground, placing a second pipe line along and closelyadjacent to said oil pipe line but spaced therefrom, said second pipeline also being supported by said frozen ground, and being disposedadjacent to said frozen ground, providing insulation between said oiland second pipe lines, and passing cold natural gas through said secondpipe line at a temperature substantially below the temperature of theadjacent frozen ground, thereby maintaining said last mentioned groundfrozen but without cooling the oil in the oil pipe line down to atemperature which would substantially reduce the flow of said oil insaid oil pipe line, including providing said oil and said natural gasfrom a common source.

10. A system for transporting oil by pipe line across frozen groundwithout melting or softening the ground by heat transfer from the oil,which comprises an oil pipe line supported by frozen ground, a secondliquid natural gas pipe line disposed closely adjacent to andsubstantially parallel to said oil pipe line, but spaced therefrom, saidsecond pipe line also being supported by said frozen ground, insulatingmeans positioned between said oil and second pipe line, means forpumping oil through said oil pipe line and including a plurality of oilpumping stations along said oil pipe line, a plurality of liquid naturalgas pumping stations along said liquid natural gas pipe line, each ofsaid oil pumping stations being positioned adjacent corresponding liquidnatural gas pumping stations, means for initially liquefying natural gasto provide said liquid natural gas and means for supplying said liquidnatural gas to said second liquid natural gas pipe line, a well headsupplying oil and natural gas, means for supplying said oil to said oilpipe line and means for supplying said natural gas to said initialliquid natural gas liquefying means, and means for maintaining thetemperature of said liquid natural gas pumped through said second pipeline substantially below the temperature of the adjacent frozen groundsupporting said oil pipe line, to thereby maintain said last mentionedground frozen.

II. A system as defined in claim 10, said insulating means including asubstance selected from the group consisting of gravel, earth, sand andair.

12. A system as defined in claim 11, said insulating means alsoincluding a supporting member for said oil pipe line.

13. A system as defined in claim 10, having a substantially smallerdiameter than said oil pipe line, said oi] pipe line and said secondliquid natural gas pipe line being disposed in an excavation below thesurface of said ground, said oil pipe being positioned above said secondliquid natural gas pipe line.

14. A system as defined in claim 13, said insulating means including asubstance selected from the group consisting of gravel and earth, andsaid substance surrounding a substantial portion of the periphery ofsaid oil pipe line.

15. A system as defined in claim 14, including means anchoring said oilpipe line in position in said excavation and supported on said gravel orsaid earth therein.

16. A system as defined in claim 13, said insulating means including aninsulating trough or cradle member positioned in said excavation, saidoil pipe line being positioned within said member adjacent the bottomthereof, said second liquid natural gas line being positioned below saidmember and adjacent the bottom of said excavation.

'17. A system as defined in claim 16, said insulating means alsoincluding a substance selected from the group consisting of gravel andearth positioned within said member, and said substance also positionedin said excavation around said member and around said liquid natural gaspipe line.

18. A system as defined in claim 16, said insulating means alsoincluding a substance selected from the group consisting of gravel andearth positioned in said excavation around said member and around saidliquid natural as pipe line, a block member positioned within said memer on the bottom thereof, said oil pipe line being positioned on saidblock in said member, a space in said member around said oil pipe line,and ambient air in said space and further insulating said oil pipe linefrom the adjacent ground.

19. A system as defined in claim 10, said second pipe line having asubstantially smaller diameter than said oil pipe line, said insulatingmeans comprising a gravel bed positioned on the surface of said ground,said oil pipe line being supported on said gravel bed and said liquidnatural gas line being positioned within said gravel bed below said oilpipe line and adjacent the surface of said frozen ground.

20. A system as defined in claim 10, said second pipe line having asubstantially smaller diameter than said oil pipe line, said insulatingmeans comprising a gravel bed positioned on the surface of said ground,said oil pipe line being supported on said gravel bed and said liquidnatural gas line being positioned in said ground jest below the surfacethereof and below said gravel bed supporting said oil pipe line.

21. A system as defined in claim 10, including liquid natural gasliquefying means at each liquid natural gas pumping station forliquefying vaporous natural gas formed in said liquid natural gas duringpassage thereof from one liquid natural gas pumping station to the nextliquid natural gas pumping station, for reducing the temperature of saidliquid natural gas at said next station, means for bypassing a minorportion of natural gas at each liquid natural gas pumping station andusing same to operate the adjacent corresponding oil pumping station,and means for bypassing an additional minor portion of liquid naturalgas at each liquid natural gas pumping station for operating said lastmentioned pumping station.

22. A system as defined in claim 10, including a third liquid naturalgas pipe line, means connecting said second liquid natural gas pipe lineto said third liquid natural gas pipe line at each of said liquidnatural gas pumping stations, and valve means in said second and thirdliquid natural gas pipe lines to provide closed loops between successiveliquid natural gas pumping stations for circulating liquid natural gasthrough said loops for initially freezing said ground.

UNITED STATES PATENT OFFICE CERTIFICATE, OF CORRECTION Patent No.3,650,119 Dated March 21, 1972 Inventor(s) Joseph T. Sparling It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below: 1

Column 4, line 72, change "with" to within line 74, delete "within" andsubstitute -30-- therefor. Column 5, line 62, after "terrain" insert--l4. 7 Column 8, line 1, delete "Siberia, and insert -frozen-. Column9, line 47, after "10, insert said second pipe line-'; line 5l,'-before"being" insert --line--. Column 10, line 35, change "jest" to just--.

Signed and sealed this 25th day of July 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOT'I'SCHALK Attesting Officer 1Commissioner of Patents FORM Po-1os0 (10-69) USCOMM-DC 60376-P69 U15.GOVERNMENT PRINTING OFFICE: I969 0-366-33A

1. A method for transporting oil by pipe line across frozen groundwithout melting or softening the ground by heat transfer from the oil,which comprises passing oil through a pipe line supported by frozenground, said oil being at a temperature substantially above thetemperature of said ground, placing a second pipe line along and closelyadjacent to said oil pipe line but spaced therefrom, said second pipeline also being supported by said frozen ground, and being disposedadjacent to said frozen ground, providing insulation between said oiland second pipe lines, and passing liquid natural gas through saidsecond pipe line at a temperature substantially below the temperature ofthe adjacent frozen ground, thereby maintaining said last mentionedground frozen but without cooling the oil in the oil pipe line down to atemperature which would substantially reduce the flow of said oil insaid oil pipe line, including providing said oil and said natural gas ingaseous form from a common source, and liquefying said natural gas priorto passage thereof through said second pipe line.
 2. A method as definedin claim 1, said insulation including a substance selected from thegroup consisting of gravel, earth, sand and air.
 3. A method as definedin claim 1, said insulation including a substance selected from thegroup consisting of gravel and earth, and comprising placing saidsubstance around said oil pipe line.
 4. A method as defined in claim 1,including pumping said oil at a plurality of stations along said oilpipe line and pumping said liquid natural gas at a plurality of stationsalong said second pipe line, the temperature of said liquid natural gasincreasing from one liquid natural gas pumping station to the nextliquid natural gas pumping station by removal of heat from said groundadjacent said oil pipe line between said last mentioned pumpingstations, and reducing the temperature of the natural gas at said nextpumping station substantially to the temperature of said natural gas atsaid preceding pumping station.
 5. A method as defined in claim 4, aportion of said liquid natural gas being vaporized during passagethereof from said one liquid natural gas pumping station to said nextliquid natural gas pumping station, and including liquefying saidvaporized natural gas at said next liquid natural gas pumping stationfor said reducing said temperature of said liquid natural gassubstantially to the temperature of said liquid natural gas at saidpreceding pumping station.
 6. A method as defined in claim 5, said oilpipe line pumping stations and said liquid natural gas pipe line pumpingstations being respectively positioned at adjacent locations along saidrespective pipe lines, including bypassing a minor portion of liquidnatural gas from said liquid natural gas pipe line at each stationthereof to the adjacent oil pipe line pumping station for operation ofthe pump at said last mentioned pumping station and to the pump at saidliquid natural gas pumping station, for operation of said respectivepumps.
 7. A method as defined in claim 5, wherein the temperature ofsaid liquid natural gas between two successive liquid natural gaspumping stations ranges from about -200* to about -275* F. at onestation, and being heated during passage from said one station up toabout -125* to about -175* F. at the next station.
 8. A method asdefined in claim 1, including initially circulating liquid natural gasthrough said liquid natural gas pipe line in a closed loop between apair of successive liquid natural gas pumping stations to reduce thetemperature of the adjacent ground to insure that said ground isinitially in a frozen condition, prior to passing oil through said oilpipe line.
 9. A method for transporting oil by pipe line across frozenground without melting or softening the ground by heat transfer from theoil, which comprises passing oil through a pipe line supported by frozenground, said oil being at a temperature substantially above thetemperature of said ground, placing a second pipe line along and closelyadjacent to said oil pipe line but spaced therefrom, said second pipeline also being supported by said frozen ground, and being disposedadjacent to said frozen ground, providing insulation between said oiland second pipe lines, and passing cold natural gas through said secondpipe line at a temperature substantially below the temperature of theadjacent frozen ground, thereby maintaining said last mentioned groundfrozen but without cooling the oil in the oil pipe line down to atemperature which would substantially reduce the flow of said oil insaid oil pipe line, including providing said oil and said natural gasfrom a common source.
 10. A system for transporting oil by pipe lineacross frozen ground without melting or softening the ground by heattransfer from the oil, which comprises an oil pipe line supported byfrozen ground, a second liquid natural gas pipe line disposed closelyadjacent to and substantially parallel to said oil pipe line, but spacedtherefrom, said second pipe line also being supported by said frozenground, insulating means positioned between said oil and second pipeline, means for pumping oil through said oil pipe line and including aplurality of oil pumping stations along said oil pipe line, a pluralityof liquid natural gas pumping stations along said liquid natural gaspipe line, each of said oil pumping stations being positioned adjacentcorresponding liquid natural gas pumping stations, means for initiallyliquefying natural gas to provide said liquid natural gas and means forsupplying said liquid natural gas to said second liquid natural gas pipeline, a well head supplying oil and natural gas, means for supplyingsaid oil to said oil pipe line and means for supplying said natural gasto said initial liquid natural gas liquefying means, and means formaintaining the temperature of said liquid natural gas pumped throughsaid second pipe line substantially below the temperature of theadjacent frozen ground supporting said oil pipe line, to therebymaintain said last mentioned ground frozen.
 11. A system as defined inclaim 10, said insulating meAns including a substance selected from thegroup consisting of gravel, earth, sand and air.
 12. A system as definedin claim 11, said insulating means also including a supporting memberfor said oil pipe line.
 13. A system as defined in claim 10, having asubstantially smaller diameter than said oil pipe line, said oil pipeline and said second liquid natural gas pipe line being disposed in anexcavation below the surface of said ground, said oil pipe beingpositioned above said second liquid natural gas pipe line.
 14. A systemas defined in claim 13, said insulating means including a substanceselected from the group consisting of gravel and earth, and saidsubstance surrounding a substantial portion of the periphery of said oilpipe line.
 15. A system as defined in claim 14, including meansanchoring said oil pipe line in position in said excavation andsupported on said gravel or said earth therein.
 16. A system as definedin claim 13, said insulating means including an insulating trough orcradle member positioned in said excavation, said oil pipe line beingpositioned within said member adjacent the bottom thereof, said secondliquid natural gas line being positioned below said member and adjacentthe bottom of said excavation.
 17. A system as defined in claim 16, saidinsulating means also including a substance selected from the groupconsisting of gravel and earth positioned within said member, and saidsubstance also positioned in said excavation around said member andaround said liquid natural gas pipe line.
 18. A system as defined inclaim 16, said insulating means also including a substance selected fromthe group consisting of gravel and earth positioned in said excavationaround said member and around said liquid natural gas pipe line, a blockmember positioned within said member on the bottom thereof, said oilpipe line being positioned on said block in said member, a space in saidmember around said oil pipe line, and ambient air in said space andfurther insulating said oil pipe line from the adjacent ground.
 19. Asystem as defined in claim 10, said second pipe line having asubstantially smaller diameter than said oil pipe line, said insulatingmeans comprising a gravel bed positioned on the surface of said ground,said oil pipe line being supported on said gravel bed and said liquidnatural gas line being positioned within said gravel bed below said oilpipe line and adjacent the surface of said frozen ground.
 20. A systemas defined in claim 10, said second pipe line having a substantiallysmaller diameter than said oil pipe line, said insulating meanscomprising a gravel bed positioned on the surface of said ground, saidoil pipe line being supported on said gravel bed and said liquid naturalgas line being positioned in said ground jest below the surface thereofand below said gravel bed supporting said oil pipe line.
 21. A system asdefined in claim 10, including liquid natural gas liquefying means ateach liquid natural gas pumping station for liquefying vaporous naturalgas formed in said liquid natural gas during passage thereof from oneliquid natural gas pumping station to the next liquid natural gaspumping station, for reducing the temperature of said liquid natural gasat said next station, means for bypassing a minor portion of natural gasat each liquid natural gas pumping station and using same to operate theadjacent corresponding oil pumping station, and means for bypassing anadditional minor portion of liquid natural gas at each liquid naturalgas pumping station for operating said last mentioned pumping station.22. A system as defined in claim 10, including a third liquid naturalgas pipe line, means connecting said second liquid natural gas pipe lineto said third liquid natural gas pipe line at each of said liquidnatural gas pumping stations, and valve means in said second and thirdliquid natural gas pipe lines to provide closed loops between successiveliquid natural gas pumping stations fOr circulating liquid natural gasthrough said loops for initially freezing said ground.